This invention relates to safety shut-off systems for agricultural irrigation systems, and, more particularly, to an improved wireless safety shut-off system that is reliably operable over an extended range of several miles.
In irrigation systems used in agricultural applications, a typical irrigation system consists of an electrically powered pivot system that circles a field comprising an agricultural crop. The irrigation system further includes a pumping unit that is usually a distance of several thousand feet or even a few miles from the pivot system. To avoid costly damage and wasted resources, the pivot system and pump unit has an automatic shut-off that is triggered by a loss in water pressure, a burn out of underground electrical lines, or a pipe breakage between the pump unit and the pivot system. Malfunctions of the drive motor on the pivot system tower or misalignment of the pivot system could also trigger an automatic shut-off of the pivot system and the pump unit.
In the conditions described, the result could be costly if the pivot system and the pump unit did not shut down properly. For instance, water could run in one place which would result in the system not restarting and could cause the field to erode and damage the crop and hamper harvesting. If an underground pipe broke, a large hole could form in the field that would require costly repairs. If the system was being used to spray nitrogen and the system kept watering, but the system stopped in one place, the nitrogen could harm the crop. Further, a stalled system could cause wastefulness in the use of water, fuel, and chemicals.
In practice, if a farmer does not have an operational safety on his irrigation system, he must operate his system manually with human supervision of the system""s operating condition, or he risks severe damage to his crops. Electricity rates are generally cheaper during off-peak hours. Therefore, the farmer must stay awake and supervise the irrigation system at night to reduce costs by taking advantage of the lowest electricity rates.
In the prior art there are wireless type safety systems that are generally being used for water system control and sewage pump stations. However, these wireless systems are generally expensive because of the cost of materials to provide a reliable safety control system. For example, the cost of materials for a safety control system for one irrigation pivot system and one pumping unit would be a minimum of $4000 using known wireless systems. A system this expensive is generally cost prohibitive to farmers.
Other systems have been proposed that use radio waves for switching loads on and off. The systems include a radio transmitter and receiver and work well, except for two major faults. These prior radio wave wireless systems operated by having a transmitter and receiver in the line of sight of each other only. Further, these prior radio wave systems had a range of less than a mile. These disadvantages or faults cause the known methods of using radio waves for irrigation safety control systems to be impracticable because of the distance between a pivot system and a pumping unit in an irrigation system. Other known wireless systems such as cellular communications systems carry costly periodic charges.
The present invention overcomes the above-mentioned and other disadvantages of the prior art systems with a novel and improved wireless safety shut-off system that is reliably operable over an extended range of several miles.
The present invention provides a wireless irrigation control safety system having a range of two to four miles by using a transmitter operating at 10 watts and providing a 27.255 MHz frequency digital signal. A receiver is provided for receiving said digital signal. The extended range transmitter product used by the present invention is also used in the home security industry. However, this product and receiver did not prove to be very dependable for use in an irrigation control safety system without further improvement. In the known applications using the extended range transmitter and receiver disclosed herein, the transmitter sends one signal to the receiver. If the receiver does not recognize or receive the signal, nothing happens. Experiments found the receiver would fail to receive a signal about 10% of the time, which is an unacceptable fault rate for a critical function such as irrigation system safety control.
In the present invention, a signal is sent every 30 seconds from the transmitter to the receiver. The signal received from the transmitter causes the system to continue running. The signal is used at the receiver to latch a relay in the made position (pump on). This relay starts timing off at an adjustable rate, for example 100 seconds, when a signal is received from the transmitter by the receiver. Every time a signal is sent from the transmitter, the latch relay starts back at timing off at 100 seconds. This latch relay with time delay allows the receiver to miss three signals from the transmitter before the system will safety-off.
Therefore, it is an object of the invention to provide an inexpensive and simple wireless safety shut-off system for agricultural crop irrigation systems.
It is another object of the invention to provide a wireless safety shut-off system that is very reliable.
It is yet another object of the invention is to provide a wireless safety shut-off system having a range of at least two miles.
Still a further object of the invention is to provide a wireless safety shut-off system for agricultural crop irrigation systems that may be packaged and marketed for others to install in the quantity required by the user.
And another object of the invention is to provide a means to replace old safety wiring in agricultural irrigation systems with a reliable wireless safety shut-off system.
The above and other objects, features and advantages of this invention will become more apparent from the following detailed description, when considered in connection with the accompanying drawings.